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  5. Mistral Devstral MediumvsGPT-6 Luna
Updated Sep 2026

Mistral Devstral MediumvsGPT-6 Luna

GPT-6 Luna is cheaper than Mistral Devstral Medium at $0.1/M vs $0.4/M input tokens.

Mistral Devstral Medium and GPT-6 Luna compared across 20 shared prompts
SpecMistral Devstral MediumGPT-6 Luna
Input price$0.4/M tokens$0.1/M tokens
Output price$2/M tokens$0.5/M tokens
Context window—1.1M tokens
Weights—Closed
Free API (OpenRouter)NoNo
ReleasedJul 2025Sep 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 20 prompts both answered. Formatting stripped, words untouched.

Startup Pitch Teardown

Here's a pitch deck summary for a startup called "MindMeld AI": **Slide 1 - Vision:** "We're building the future of human-AI collaboration.…

Mistral Devstral Medium346 words
Weak Claim 1: "Works with any language, any device." Why it's weak: This claim is overly broad and may not be entirely accurate. Different languages have unique structures, and it's unlikely that a single model can achieve high accuracy across all languages without significant training data for each.
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GPT-6 Luna421 words
“94% accuracy” and “predict what you want to type before you think it” Why it’s weak: This is the deck’s central technical claim, but “accuracy” is undefined: Is it word-level or character-level accuracy, measured on a fixed vocabulary or open-ended text, and under what conditions?
Read the full answer

Adversarial Contract Review

Here is a contract for a software consulting engagement: --- SOFTWARE CONSULTING AGREEMENT This Agreement is entered into between TechCorp…

Mistral Devstral Medium958 words
Certainly! Here are the clauses that could be exploited against the contractor, along with suggested modifications and the legal reasoning behind them: SCOPE Original Clause: "Contractor shall provide software development services as directed by Client.
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GPT-6 Luna2,040 words
This agreement is strongly one-sided. The enforceability of particular terms—especially the non-compete, liability provisions, and arbitration clause—depends on the governing law and the facts. The agreement does not identify a governing law, which is itself a significant gap.
Read the full answer

Simple 7-Ingredient Recipe

Create a simple recipe for a delicious dish (sweet or savory) using only 7 common pantry ingredients. Include a creative name for the dish…

Mistral Devstral Medium248 words
Dish Name: "Pantry Pasta Primavera" Ingredients: Pasta (any shape, 8 oz or 225g) Canned tomatoes (14 oz or 400g) Garlic (2 cloves) Onion (1 medium) Olive oil (2 tbsp) Salt (1 tsp) Black pepper (1/2 tsp) Instructions: Prepare the vegetables: Finely chop the onion and mince the garlic cloves.
Read the full answer
GPT-6 Luna113 words
Crispy Parmesan Chickpeas A crunchy, savory snack with a cheesy finish Ingredients (7): 1 can chickpeas, drained and dried 1 tablespoon olive oil ½ teaspoon salt ½ teaspoon paprika ¼ teaspoon garlic powder ¼ cup grated Parmesan 1 tablespoon lemon juice Prep time: 5 minutes Cook time: 30–35 minutes Instructions: Heat…
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Beginner's Longevity Plan

Outline a simple, actionable 1-month plan for someone starting their journey towards better health and longevity. Focus on 3 key areas…

Mistral Devstral Medium442 words
1-Month Health and Longevity Plan Key Areas: Diet, Exercise, Sleep Week 1: Establish a Baseline Diet: Track your current diet using a journal or app (e.g., MyFitnessPal) to understand your eating habits. Start incorporating more fruits and vegetables into your meals. Begin reducing processed foods and sugary drinks.
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GPT-6 Luna330 words
A simple 1-month starter plan Choose three foundations: food, movement, and sleep. Aim for steady habits, not perfection. If you have a health condition, significant pain, or concerns about changing your activity or diet, check with a healthcare professional first.
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Ethical Dilemma with Stakeholders

You're the CEO of a pharmaceutical company. Your best-selling drug ($2B annual revenue, used by 4 million patients for chronic pain) has…

Mistral Devstral Medium496 words
Hour-by-Hour Action Plan: Hour 1-2: Gather Information Meet with the research team to understand the data, methodology, and certainty of the findings. Consult with the Chief Medical Officer (CMO) to assess the severity and implications of the side effect.
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GPT-6 Luna1,930 words
I would not wait six months for more data. A potentially fatal signal affecting a drug used by millions requires immediate safety assessment, prompt engagement with regulators, and a plan to inform patients and clinicians.
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Advanced Longevity Plan (Biohacker)

Develop a comprehensive, cutting-edge 3-month longevity plan for a biohacker aiming to optimize longevity, physical and cognitive…

Mistral Devstral Medium690 words
3-Month Longevity Optimization Plan for Biohackers Month 1: Foundation Building Week 1-2: Initial Assessment and Baseline Establishment Wearable Tracking: Devices: Oura Ring, Apple Watch, Whoop Strap Metrics to Track: Sleep quality, heart rate variability (HRV), resting heart rate, activity levels, and stress levels.
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GPT-6 Luna1,874 words
12-week longevity and performance plan This plan is for a generally healthy adult who wants to improve fitness, metabolic health, sleep, and cognitive performance—not a substitute for medical care or a promise to slow aging.
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Our Verdict
GPT-6 Luna
GPT-6 Luna
Mistral Devstral Medium
Mistral Devstral MediumRunner-up

Not enough votes to call it. On the specs, GPT-6 Luna has the edge: bigger model tier, newer, bigger context window, major provider backing.

GPT-6 Luna costs 4.0x less per token.

Slight edge

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Mistral Devstral Medium
Input
$0.40
Output
$2.00
GPT-6 Luna
Input
$0.10
4.0× cheaper
Output
$0.50
4.0× cheaper

GPT-6 Luna is cheaper on both: 4.0× input, 4.0× output.

Where to run it

3 hosts, cheapest first

Mistral Devstral Medium

No hosts listed on OpenRouter.

GPT-6 Luna3 hosts
HostInOutContextUptime
Azure AI Foundry$0.10 in·$0.50 out·1.1M·88.4% upOpenAI$0.10 in·$0.50 out·1.1M·99.9% upAmazon Bedrock$0.11 in·$0.55 out·1.1M·99.8% up

Per million tokens. Prices and uptime via OpenRouter, checked 25 Sep 2026.

Research

What we learned reading every model

FAQ

Common questions

Mistral Devstral Medium is developed by Mistral AI while GPT-6 Luna is developed by OpenAI. You can compare their actual outputs across 20 challenges on Rival to see how they differ in practice.

It depends on your use case. Mistral Devstral Medium and GPT-6 Luna each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 20 challenges so you can judge which fits your needs best.

Mistral Devstral Medium costs $0.4/M input tokens and GPT-6 Luna costs $0.1/M input tokens. GPT-6 Luna is $0.30/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

This page shows a side-by-side comparison of Mistral Devstral Medium and GPT-6 Luna across shared challenges. You can vote on which model produced the better output in a blind duel. Browsing and voting are free. No account is needed to look; signing in only saves your votes and likes.

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Model pages

Mistral Devstral Medium logo
Mistral Devstral Medium59 outputs, specs and price
GPT-6 Luna logo
GPT-6 Luna20 outputs, specs and price
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